<html>
    <head>
        <title>主页</title>
    </head>
    
    <body>
        <form method="POST">
            <label for="username">请输入用户名:</label>
            <input type="text" id="username" name="username">
            <button>进入聊天室</button>
        </form>
    </body>
</html>